Color Blindness
Color blindness changes the sensitivity of the eye as a function of wavelength. For people with protanopia, the peak of the eye's response is shifted toward the short-wave part of the spectrum (approximately 540 nm), while for people suffering deuteranopia, there is a slight shift in the peak of the spectrum, to about 560 nm. People with protanopia have essentially no sensitivity to light of wavelengths more than 670 nm.
Most mammals other than primates have the same luminosity function as people with protanopia. This makes it possible to study the nocturnal life of animals by illuminating the scene with long-wavelength red light that they can't see.
For older people with normal color vision, the crystalline lens may become slightly yellow due to cataracts, which moves the maximum of sensitivity to the red part of the spectrum and narrows the range of perceived wavelengths.
Read more about this topic: Luminosity Function
Famous quotes containing the words color and/or blindness:
“Gradually I regained my usual composure. I reread Pale Fire more carefully. I liked it better when expecting less. And what was that? What was that dim distant music, those vestiges of color in the air? Here and there I discovered in it and especially, especially in the invaluable variants, echoes and spangles of my mind, a long ripplewake of my glory.”
—Vladimir Nabokov (1899–1977)
“It amazes me when I hear any person prefer blindness to deafness. Such a person must have a terrible dread of being alone. Blindness makes one totally dependent on others, and deprives us of every satisfaction that results from light.”
—Horace Walpole (1717–1797)